GHC 7.6 is rejecting some programs that I think ought to be well-typed.
Details here https://gist.github.com/3842579
I find this behavior particularly odd because I can get GHC to deduce
the type equalities in some contexts but not in others. In particular,
it does not deduce them inside of type class instances.
Is this a known issue? I'll create a Trac ticket if that's appropriate.
Thanks for your time.